The present invention relates to the method and the device for pre-recording information such as track-address and sector address on the read/write optical disk.
The optical disk capable of reading/writing which is commonly used today has pre-grooves and sector marks (tracking information, sector address, etc.) written beforehand along the rotation surface on the disk, and read/write of the data pit which is additionally recorded, for example, by a user is preformed based on these pre-grooves and sector marks. The disk having these pre-grooves and sector marks is now reproduced and manufactured with a sort of mold called a stamper, by using the process which is similar to that in manufacturing popularly-used audio disks. The disks manufactured in this process are called replica disks. There has been proposed a production method of writing the pre-grooves and sector marks by light beams on every single disk; what is called a servo write system. Thus the optical disk now generally used is of depth phase structure that has two kinds of depth; the sector marks have a depth of .lambda./4 and the pre-grooves have .lambda./8.
However, the optical disk which has a structure with two different kinds of depth as mentioned above is not easy to manufacture by using the servo write system.
Accordingly, there has been made a proposal by the present inventor and others with reference to a record/reproduction optical disk that does not require the above-said pre-groove or two different-depth structure.
This system is described in the Japanese Patent Application Laid Open No. 91537/1983, corresponding to U.S. Pat. No. 4,541,082 or German Patent Application No. 3243685.8, and the following is the general outline of the system.
In this system, a servo area (which is equivalent to the area of the above-mentioned sector marks) is formed for recording tracking information to which more than two pits are intermittently provided previously along the tracks and subsequently to this servo area, a data area (which is the area to which, for example, a user makes an additional record as previously stated, and which therefore has no record written in) is provided for recording the data pit.
The servo area and the data area constitute a single sector, and a large number of such sectors lying in a line comprise tracks. In recording the data pits, the system performs tracking based on tracking information which is obtained from the pre-pits (on which information such as tracking information and sector addresses is written) pre-written in the servo area. In the data area, the system records the data pits while holding the tracking information obtained from the servo area.
In addition, the system for detecting tracking information transmitted from the pre-pits which are written in the servo area here does not employ a Push-Pull system, but uses what is called a heterodyne system. There have been proposed a variety of circuit systems in this detection system. Such circuit systems are described, for example, in the Japanese Patent Application Laid Open No. 91538/1983 corresponding to U.S. Pat. No. 4,541,082, Japanese Patent Application Laid Open No. 93222/1977 corresponding to U.S. Pat. No. 4,057,833, etc. This heterodyne system is characterized in that tracking information can be obtained if the pits is of .lambda./4 depth phase structure or of black and white structure (amplitude structure).